AND EMBRYONIC FORMS. 429 



Remarks. — The specimens of this species received from Mr. Moores were not in 

 very good order, and the colors described may not be perfectly correct from that 

 cause. A dried specimen, sent to me by my brother, T. G. Lea, in 1838, has the 

 following note on the paper to which it was attached. " U. trigonus, the stomach 

 opened, showing the red internal part ; it is white externally. The red portion may 

 be the ovary or the ova, before they are transferred to the branchiae." 



Unio solidtjs, Lea. Trans. Amer. Phil. Soc, (2), vol. vi. pi. 5, fig. 13. Obs. vol. ii. p. 13. 



All the specimens received seemed to be males. 



Branchice large, semicircular, inner ones much the larger, free nearly the whole 

 length of the abdominal sack. Palpi rather large, subelliptical, united half way 

 down the posterior edges. Mantle thin, thickened along the edges. Branchial opening 

 rather large, with numerous small, closely crowded papillte. Anal opening rather 

 large, finely crenulate on the inner edges. Super-anal opening rather large, and united 

 for some distance below. Color of the mass whitish or salmon. 



Columbus, Ohio, H. Moores. 



Unio cornutus, Bar. Am. Jour. Science, vol. vi. p. 122. 



Branchial uterus occupies the posterior inferior part of the outer branchia? in six or 

 seven ovisacks pendent below the edge of the branchial leaf. Branchice rather small, 

 rounded below, inner ones much the larger, free nearly the whole length of the 

 abdominal sack. Palpi rather small, subtriangular, united half way down the pos- 

 terior edges. Mantle very thin, with a very broad thin margin. Branchial opening 

 small, with numerous small thickly set papillas. Anal opening very small, with ap- 

 parently very small crenulations. Super-anal opening very large, united below for 

 some distance. Color of the mass whitish, inclining to faint salmon-color. 



Cincinnati, Ohio, J. Clark. 



RemarJcs. — The position and appearance of the ovisacks are remarkable. In two 

 specimens, one had six in each of the outer branchios, and the other had seven, and 

 these are in a curve of the posterior part of the branchios hanging below the edge of 

 the leaf. 



Unio pustulatus, Lea. Trans. Amer. Phil. Soc, (2), vol. iv. pi. 7 fig. 9. Obs. vol. i. p. 89. 



Branchial uterus . No ova were found here, but they were in the ovarium. 



These ova appeared to be more elliptical than round. Branchial large, thin, nearly - 

 semi-circular, free two-thirds the length of the abdominal sack. Palpi not large, trans- 

 verse, suboval, united half way down the posterior edges. Mantle thin, thicker and 

 slightly colored on the margin. Branchial opening rather large, with numerous small 

 papillae. Anal opening very small, with minute papilla?. Super-anal opening very 



109 



